Electro static discharge (ESD) is often undesirable in the fabrication process of thin film transistor liquid crystal display (TFT-LCD). ESD may seriously affect product yield.
When forming a TFT-LCD device, the glass substrate may be in contact with or rub against the machine used for forming layers on the glass substrate. In this case, electrostatic charges may accumulate on surface of the glass substrate. An electrostatic discharge happens when the electrostatic charges have accumulated to a certain level or when the curvature in some locations increases as the glass substrate contacts the machine. The electrostatic discharge breaks the layers formed on the glass substrate. The electrostatic discharge may also cause short circuit between different layers and may thus generate defects. Especially for the wiring area surrounding the display region of the display substrate, more defects are generated due to the electrostatic discharge and the intensive distribution of circuit lines in the wiring area.
In the actual manufacturing process, formation of electrostatic charges may be avoided by adjusting location of contact points with the machine to avoid contacting the charge-sensitive wiring area surrounding the display region or by adding an ion fan in the manufacturing line. However, these methods may not effectively avoid the formation of electrostatic charges.
FIG. 1 illustrates a top view of two circuitry elements which may discharge frequently in a wiring area of a conventional array substrate. As shown in FIG. 1, in a wiring area, a first circuitry element 5 includes a gate metal layer, and a second circuitry element 6 includes gate lines and multiple layers formed thereon. As shown in FIG. 1, a right-angle area 51 of the first circuitry element 5 is adjacent to the second circuitry element 6 having a corresponding area 61. Electrostatic discharge often occurs between the right-angle area 51 and the corresponding area 61.
As shown in FIG. 2, because there is only a single metal layer in the first circuitry element 5, the electrostatic discharge does not affect the circuit lines too much. The second circuitry element 6 includes a multilayer structure formed by multiple semiconductor layers covering the gate lines, which are at the same layer as for the active region of the transistors. When discharging, the electrostatic discharge between the first circuitry element 5 and the second circuitry element 6 easily breaks through an insulating layer between the semiconductor layer and the gate lines and causes short circuit to affect driving of the display substrate.
Conventional methods to solve the discharging problem between the first circuitry element 5 and the second circuitry element 6 include using a rounded angle to replace the right angle in the first circuitry element 5 and the second circuitry element 6. Another method to solve the discharging problem includes increasing the distance between the first circuitry element 5 and the second circuitry element 6 in the wiring area. However, these methods may not be equally effective on different types of display substrates and may not indeed solve the problems of display substrates due to the electrostatic discharge.
The disclosed display substrate, display panel, and display apparatus are directed to at least partially alleviate one or more problems set forth above and to solve other problems in the art.